ASTM_D_4338_-_97_2021.pdf

Designation:D433897(Reapproved 2021)Standard Test Method forFlexibility Determination of Supported Adhesive Films byMandrel Bend1This standard is issued under the fixed designation D4338;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This test method covers the determination of the flex-ibility of an adhesive film bonded to a flexible substrate.Theresults are useful for comparing flexibility of adhesives and notfor absolute characterization of adhesives.1.2 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are provided forinformation purposes only.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D609 Practice for Preparation of Cold-Rolled Steel Panelsfor Testing Paint,Varnish,Conversion Coatings,andRelated Coating ProductsD907 Terminology of AdhesivesD3111 Practice for Flexibility Determination of Hot-MeltAdhesives by Mandrel Bend TestE171 Practice for Conditioning and Testing Flexible BarrierPackaging3.Terminology3.1 DefinitionsFor terms used in this standard,refer toTerminology D907.3.2 Definitions of Terms Specific to This Standard:3.2.1 mandrel,ncylindrical rod.4.Summary of Test Method4.1 A test substrate coated with a film of adhesive,properlysized and conditioned,is folded to form an inverted U-shapedangle over the mandrel maintaining intimate contact with thenon-adhesive side.Using a fresh specimen for each test,thetest is repeated with progressively smaller diameter mandrelsuntil the adhesive fails(cracks)on bending.The flexibilityvalue of the adhesive is the smallest diameter mandrel overwhich four out of five test specimens do not break.5.Significance and Use5.1 The mandrel bend test is simple and fast.It requires littleinvestment in equipment and little operator training.The primepurpose is to determine whether a film of adhesive coated on asubstrate meets flexibility requirements.The test is also usefulfor comparing flexibility of adhesives.It can be used to designadhesives by comparing the flexibility of various formulationsto meet specific end-use parameters.The adhesive flexibilitycan be determined at temperatures other than ambient byconditioning the test apparatus and test specimen at the desiredtemperature and performing the test under those conditions.6.Apparatus6.1 The test apparatus consists of a series of differentdiameter cylindrical rods or mandrels supported at each end.These should be long enough to permit placement of the flatside of a test specimen tangentially at right angles to thelongitudinal axis of the test mandrel.Individual requirementsdetermine the diameter and lengths of the rods needed.Formost tests,rods 3.2 mm(18in.),6.4 mm(14in.),and 12.8 mm(12in.)in diameter,by 75 to 150 mm(3 to 6 in.)in length,made of brass or stainless steel,are satisfactory.Two simple1This test method is under the jurisdiction of ASTM Committee D14 onAdhesives and is the direct responsibility of Subcommittee D14.10 on WorkingProperties.Current edition approved April 1,2021.Published April 2021.Originallyapproved in 1984.Last previous edition approved in 2016 as D4338 97(2016).DOI:10.1520/D4338-97R21.This test method is intended to replace Method 1081 of Federal TestMethod 175A.Available from DLADocument Services,Building 4/D,700 RobbinsAve.,Philadelphia,PA 19111-5094,http:/quicksearch.dla.mil.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1test frames are shown in Fig.1,one with fixed mandrels,andthe other designed to tak